Filoviruses, such as Ebola (EBOV) and Marburg (MARV), arenaviruses, such as Lassa fever (LFV) and Junin (JUNV), and rhabdoviruses, such as vesicular stomatitis virus (VSV) and rabies virus (RABV), are enveloped RNA viruses that can cause severe disease in humans and animals. For example, Filovirus and arenavirus infections can result in hemorrhagic syndromes with high mortality rates in humans, and as such, these viruses are classified as NIAID Category A priority pathogens (Feldmann et al., 1996. Filoviruses. In Baron S (ed.), Medical Microbiology, 4th Ed, Galveston (Tex.); Feldmann et al., 1996, Adv. Virus Res. 47:1-52; Grant et al., 2012, Viruses 4:2317-2339; Peters et al., 1989, Rev. Infect. Dis. 11 Suppl 4:S743-749). There are currently no FDA-approved vaccines or therapeutics to control infection and transmission of EBOV, MARV and JUNV, and the FDA-approved drug to treat LVF (ribavirin) has low efficacy in treating the disease.
The matrix proteins of filoviruses (VP40), arenaviruses (Z), and rhabdoviruses (M) are highly abundant and play key roles in promoting virus assembly and egress (Hartlieb et al., 2006, Virol. 344:64-70; Jasenosky et al., 2004, Virus Res. 106:181-188; Liu et al., 2010, Future Virol. 5:481-491). For example, independent expression of EBOV or MARV VP40 leads to the production of virus-like particles (VLPs) that accurately mimic the morphology and budding characteristics of live infectious virus (Hartlieb et al., 2006, Virol. 344:64-70; Jasenosky et al., 2004, Virus Res. 106:181-188; Liu et al., 2010, Future Virol. 5:481-491). A common feature of these various viral matrix proteins is the presence of one or more motifs referred to as Late (L) budding domains. The conservation of L-domains within the matrix proteins of filoviruses, arenaviruses, rhabdoviruses, paramyxoviruses, and retroviruses suggests that they are generally important and required for efficient RNA virus budding (8). Viral L-domains recruit host ESCRT (endosomal sorting complex required for transport) complexes to mediate efficient virus-cell separation (or “pinching-off”), and consist of core consensus amino acid motifs such as PPxY, P(T/S)AP (PTAP), YxxL, or FPIV (x is any amino acid).
Viral L-domain/host interactions are important for efficient virus egress and spread. For example, the PPxY motif mediates interactions with WW-domains within mammalian E3 ubiquitin ligase neural precursor cell expressed developmentally down-regulated protein 4 (“Nedd4”) to facilitate virus egress. Nedd4 is associated with the ESCRT machinery and mono-ubiquitinates ESCRT proteins as well as viral matrix proteins (Liu et al., 2010, Future Virol. 5:481-491). A functional PPxY motif is present in the matrix proteins of EBOV, MARV, VSV, RABV, LFV, and others. Thus, recruitment of host proteins such as Nedd4 by viral L-domains represents a broad-spectrum target for the identification and advancement of antiviral drugs hypothesized to dampen virus egress from infected cells, thereby reducing virus dissemination and disease progression.
There is an unmet need for the identification and development of potent, broad-spectrum antiviral agents, particularly those that can target high priority pathogens for which no current treatments are available. In particular, there is an unmet need for the development of safe and effective therapeutics against biodefense and high priority viral pathogens, including filoviruses (e.g., Ebola and Marburg) and arenaviruses (e.g., Lassa fever and Junin), which cause severe hemorrhagic fever syndromes with high mortality rates. The present invention addresses and meets these needs.